HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Corey, J. C. Articles by Green, R. E. Search for Related Content PubMed Articles by Corey, J. C. Articles by Green, R. E. Agricola Articles by Corey, J. C. Articles by Green, R. E.

Miscible Displacement Measurements within Laboratory Columns Using the Gamma-photoneutron Method¹

ABSTRACT

When fluid in a porous medium is displaced by a second fluid that is miscible with the first, a transition zone exists between the two. The length and location of this transition zone in a soil column is difficult to measure in situ. When one of the fluids contains D₂O as the major component, a new procedure, the gamma-photoneutron method, readily measures this transition zone. This method permits precise measurements of the average concentration of heavy water (D₂O) at selected locations in a soil column. The utility of the method is illustrated by two experiments; the downward displacement of D₂O (specific gravity of 1.105 g/cm³) by H₂O, and the downward displacement of H₂O by D₂O + NaNO₃ (specific gravity of 1.291 g/cm³). The mathematical model which describes the shape of the transition zone between the miscible fluids requires the apparent diffusion coefficients to be constant. The experiment showed the apparent diffusion coefficient was not constant as the zone moved through a 100-cm column. Unstable flow due to viscosity differences between fluids was probably responsible for increases in the apparent diffusion coefficient when H₂O displaced D₂O.

¹ Joint contribution from the Savannah River Lab., E. I. du Pont de Nemours & Co., Aiken, S.C. 29801 and the Univ. of Hawaii, Honolulu, 96822. Approved for publication as Hawaii Agri. Exp. Sta. Journal Series no. 1192. The information contained in this article was developed during the course of work under Contract AT(07-2)-1 with the US Atomic Energy Commission.

² Research Physicist, Research Chemists, Savannah River Lab. and Associate Professor of Soil Science, Univ. of Hawaii. The work was done while the fourth author was an Oak Ridge Associated Universities Research Participant at the Savannah River Lab.

Received for publication April 27, 1970. Accepted for publication August 3, 1970.